New Delhi, May 1 : Ace investor Warren Buffett's Berkshire Hathaway Inc is back in the market as his conglomerate made roughly $41 billion of net purchases in the first quarter, the media reported. Bloomberg reported that the purchase provided a boost to its Chevron Corp stake that vaulted the investment into Berkshire's top four common stock holdings. His stock buyings were thwarted due high valuations. Buffett also disclosed that the company now holds an expanded 9.5 per cent stake in Activision Blizzard Inc. stock -- an arbitrage bet on the video-game maker in the midst of being acquired by Microsoft Corp, the Bloomberg report said. Berkshire has not been this significant of a net buyer of common stocks in any quarter in data going back to 2008, it added. The purchases in the first quarter helped chip away at Berkshire's cash pile, which ended the quarter at $106 billion, the lowest since the third quarter of 2018. /IANS